SODA was developed in the 1990s as a collaborative project between the Department of Atmospheric and Oceanic Science at the University of Maryland and the Department of Oceanography at Texas A&M University with the goal of providing an improved estimate of ocean state from those based solely on observations or numerical simulations.
As part of the data assimilation scheme, the system ingests a wide variety of observations including hydrographic profiles, ocean station data, moored temperature and salinity measurements, surface temperature and salinity observations from a variety of instruments (e.g., MBT, XBT, CTD), sea surface temperature (SST) from nighttime infrared observations from satellites, and satellite based sea level altimetry.
Standard state variables were calculated including temperature, salinity, zonal and meridional velocities, and sea level, as well as several derived fields such as heat content.
[2] In addition to the 61-year reanalysis data set, a “beta” version (i.e., currently being evaluated), SODA 2.2.4, was released in 2010 and extends from 1871 to 2008 with monthly temporal resolution.
This extended analysis is identical in horizontal and vertical spatial resolution as the standard reanalysis data set (SODA 2.1.6), and includes similar output variables.